JPH02243914A - Three-dimensional coordinate measuring instrument - Google Patents

Abstract

PURPOSE:To accurately measure the three-dimensional coordinates of a measurement point by providing a means which calculates the three-dimensional coordinate position of the measurement point and the position error of the three- dimensional coordinate position of a standard detected previously by a detecting means as to the measurement point. CONSTITUTION:A master object is set on a master table 10 and a robot 3 is moved to a predetermined position to pick up the image of a part to be detected by a camera 5. Then the center position coordinates of the master object on image picked-up camera coordinates are detected by a camera control means 8 and its data is sent and stored in the memory of an arithmetic means. Then when a measurement starting command is inputted from the means 8, a robot control means 7 moves an arm 4 to a 1st measurement point, the center coordinates of the detected part of a center positioning member 22 in the visual field of the camera 5 are detected, and its data is sent to the means 6. The means 6 calculates the difference between the measured coordinates and previously stored master coordinates to be transformed into work coordinates. Then the part to be measured is image picked up by similar means at >=2 different angles as to one measurement point to find three-dimensional coordinates.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a three-dimensional measuring device that uses optical means and that automatically measures the coordinates of a point in space.

(Prior art) For example, in the case of automobiles, one part and another part are assembled to complete an intermediate assembly (hereinafter referred to as a sub-assembly), and this sub-assembly is assembled into a heavy body to form a complete vehicle. It goes without saying that during manufacturing, the precision of assembly is the most important factor that affects the quality of the finished vehicle.

Particularly in the case of automobiles, which are made up of many parts, it has been possible to minimize assembly errors by improving the structure of a single part, or to develop systems that can absorb assembly errors. It is progressing.

On the other hand, efforts are being made to ensure component accuracy in manufacturing processes, such as press working and resin molding, and to improve inspection accuracy in each manufacturing process.

A three-dimensional measuring device is known as one of the means for measuring the manufacturing accuracy of such manufactured products, and this device uses optical means to accurately and quickly measure 411 fixed points on manufactured products. It is generally configured to obtain That is, as shown in FIG. 12, there is a mask table 10 on which the object to be measured 1 is fixedly mounted, a camera 5 which is an optical means fixed to this mask table 10, and data imaged by this camera 5. An image processing device 11 that calculates , and a recording device 12 that outputs the results onto recording paper 13 are added. Then, the reference point 14 on the mask table 10
The camera 5 is installed so that the measurement point 2 of the object 1 is within the field of view of the camera 5, and the mask position data of the measurement point 2 with respect to the reference point 14 is stored in advance in the memory in the image processing device 11. I'll keep it. In this state, the manufactured product 1 is placed at a predetermined position on the mask table 10 by the camera 1, and the camera 5 is used to measure the measurement point 2 of the manufactured product 1 and the reference point 14 of the mask table 10.
The image processing device 14 calculates the positional relationship between the two. At this time, the mask position data (Xo
, Yo) and the actually measured measurement point (X+,
Y,) are matched with each other by a calculation unit in the image processing device 11, and ΔX=X, -X. , ΔY=Y, -Y.

The structure is such that the position coordinates of the measurement point can be easily calculated.

(Problem to be Solved by the Invention) However, in the conventional three-dimensional measuring device mentioned above, the position within the plane perpendicular to the imaging direction of the camera (the X-Y plane) cannot be easily determined. However, the position measurement of the measurement point in the imaging direction of the camera (that is, the Z-axis direction in Fig. 12) is calculated based on the focal length of the camera. , the disadvantage is that the error in the measured values is large.

In addition, since the camera 5 is fixed at a predetermined position relative to the mask table 10, if the 10-plane configuration of the object to be measured is complex, a dedicated camera must be installed at each measurement point. Not only that, but the measuring device becomes larger and more complicated, and it is also disadvantageous in terms of cost.

Moreover, even if such a large number of cameras are provided, if the shape of the object to be measured changes, the device cannot be used as is, and its versatility is extremely poor.

Therefore, the present inventors focused on the versatility of industrial robots, and aimed to provide a measuring device that can accurately and quickly measure the three-dimensional coordinates of a fixed point using Δ{. As a result of intensive research, we have completed the present invention.

Therefore, an object of the present invention is to provide a measuring device that can accurately and quickly measure the three-dimensional coordinates of a measuring point and is also highly versatile.

(Means for Solving the Problems) The present invention for achieving the above-mentioned object has an industrial robot arm that has been taught in advance to operate in close proximity to a plurality of measurement points on an object to be measured. A position detection means for detecting a position is provided, and a calculation means for calculating a position error between the three-dimensional coordinate position of the measurement point and the three-dimensional coordinate position of a standard point with respect to the measurement point detected in advance by the detection means is shown in white.

This is a three-dimensional coordinate measuring device.

(Function) In the present invention configured as described above, first, the mask position coordinates of each of the four fixed points of the object to be measured are stored in the calculation means. After setting the object to be measured at a predetermined position, when the industrial robot operates on the object along a pre-taught trajectory, the position detection means attached to the arm of the robot detects each measurement point. Imaging 7,
This imaging data is input to a calculation means and compared with the mask position coordinates. This makes it possible to obtain the positional error of the measurement point with respect to the standard point.

(Example) Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1 shows three-dimensional coordinates/Ill according to an embodiment of the present invention.
FIG. 2 is a conceptual diagram showing the three-dimensional measuring device, and FIG. 2 is a perspective view showing the center positioning member used in the three-dimensional measuring device of the same embodiment.
The figure is a cross-sectional view taken along the line 1--2 in FIG. 2, FIG. 4 is a cross-sectional view taken along the line IV-IV in FIG. Flowcharts showing control of the means and calculation means, and FIGS. 7 to 11 are explanatory diagrams showing the coordinate transformation method of the same embodiment.

First, as shown in FIG. 1, the three-dimensional coordinate measuring device of this embodiment includes an industrial robot 3 equipped with an arm 4, a camera 5 serving as a position detection means, and a control means 7 for the industrial robot.
, camera control means 8 , calculation means 6 , and recording means 9
It is composed of.

The industrial robot 3 is a conventionally known multi-axis drive type robot, and is equipped with an arm 4 at its tip. The arm 4 of this robot is configured such that a control signal transmitted from the robot control means 7 is manually applied to an actuator (not shown) provided on each axis of the robot 3, and an encoder (not shown) similarly provided on each axis. The camera 5 is sequentially moved to a position close to the measurement point 2 of the object 1 by moving along a pre-taught trajectory while being controlled by the camera 1 .

The camera 5 attached to the tip of the arm 4 is equipped with a CC
D (Charge Coupled Device)
This CC has an element and the light that is manually generated from the field of view to be imaged is
In each pixel of D, a charge corresponding to the intensity of the light is accumulated, and the output signal for each pixel is transmitted to the camera control means 8. For example, as shown in FIG. Bracket 21 spot welded to member 20
When inspecting how much the center position of the center position has deviated from the standard position, first, a center positioning member 22, which will be described later, is set on the bracket 21. This center positioning part month 2
2 is formed with a spherical detected portion 23, and the portion other than the detected portion 23 is painted black. Therefore, the CCD on which the reflected light from the detected part 23 is incident
The pixels become brighter than the surrounding areas, and the signals of each of these pixels are sent to the camera control means 8, where the center position of the detected portion 23 can be detected accurately.

A center positioning part 22 for detecting the detected part 23
An example of this is shown in FIGS. 2-4. In the diagram “
21" is a bracket spot welded to a member (not shown) of the car body, etc., and bolt holes 24.24
For example, the end of the lower arm is inserted between the two vertical walls 25, 25, and the lower arm is fastened to the member with a bolt.

Therefore, if the welding position of the bracket relative to the member body is misaligned, the lower arm may not be assembled, or even if it is assembled, the precision of assembling the two may be insufficient, which may affect reliability. There is. Therefore, we inspect how far the center positions of the vertical walls 25, 25 of the bracket 21 are relative to the member body, and if welding is not performed within the preset specifications, we will discard or I'm trying to make corrections.

The main body portion 26 of the center positioning member 22 has insertion holes 28.28 for pins 27 that are inserted into the two bolt holes 24.24 of the bracket 21 and fixed in the vertical direction as shown in FIG.
is formed. It is desirable that the diameters of the pin 27 and the insertion hole 28 be as equal as possible to the diameter of the bolt hole 24 of the bracket 21;
? It may be slightly smaller than the diameter of the manhole 28.

Both sides 29.29 of the main body portion 26 of the single-core positioning member 22
A detection target portion 23 formed in a spherical shape is fixed by welding or the like to a center position that equally divides the distance between the two, so that the center of the sphere coincides with the center position.

In this embodiment, the parts other than the detected part 23 are painted black, thereby further emphasizing the contrast between the detected part 23 and its surroundings.

Further, in this embodiment, the detected portion 23 is formed into a spherical shape, but it is not particularly limited to this shape, as long as it has a shape that can be detected by the pixels of the camera 5 described above. As shown in FIG. 4, passages 31, 32 communicating with each other are bored in both sides 29, 29 and the front surface 30 of the main body 26 of the center positioning part +, I'22. The passageway 31 is threaded. In the figure, numeral "33" denotes a presser which is loosely inserted into the passage 32 bored in the side surface 29, 29, and its tip 33a is formed into a wedge shape. Also, two suppressors 33, 33 are placed on each side 29.29.
When the wedge-shaped tips 33a are compressed in the direction in which they abut each other, the other end 33b of the presser 33 is flush with the side surface 29 of the main body 26. And the tip 33
A wedge-shaped presser 33 is inserted from both sides 29.29, and from the front side 30, a bolt is screwed into the screw, and its tip 34a is inserted into the presser tip 33.
Adjustment bolt 34 formed in a shape corresponding to the wedge shape of a.
When screwed in, both pressers 33.33 protrude from both sides 29.29 of the main body 26 by the same dimension.

At this time, the other end 33b of the child 33 is pressed against the bracket 21.
25.25, and the main body part 2
The gap size from the side surface 29 of the bracket 6 to the vertical wall 25 is equal, so that the center position of the detected part 23 and the bracket 2 are equal.
The center positions of both vertical walls 25 and 25 of 1 can be made to coincide with each other.

The calculation means 6 shown in FIG. 1 is a control section that calculates the coordinate data of the standard point taught in advance and the coordinate data of the object to be measured 1 detected by the camera control means 8. Further, the recording means 9 is a printer that outputs the measurement results calculated by the calculation means 8. Note that this recording means 9 may be a display, or may be a combination of a display and a printer.

The mask table 10 is a stand fixed to the robot 3 for mounting a fixed object A-11, and in the case of a member 20 as shown in FIG. Members 35, 36 are provided.

Next, the measurement procedure of the three-dimensional coordinate measuring apparatus of this embodiment configured as described above will be explained with reference to FIGS. 5 to 11.

(1) Teaching the standard point (mask coordinates) First, as shown in FIG. 7, before starting measurement, place the master member 20 with the bracket 21 welded on the mask table to-, and then turn the layout machine on. is used to find the center position coordinates (Xo*'/o) of the detected part 23 on the workpiece coordinate system (Xw, Yw). For example, a certain reference point of the mask product is determined as the origin Ow of the workpiece coordinate system, and the coordinates of the center position of the detected part 23 in the Xw Yw plane are measured, or calculated from the design drawing 1[-. The mask position coordinate data (Xo, yo) in the workpiece coordinate system (Xw, Yw) obtained in this way is stored in the memory of the calculation means 6. Here, the mask position in three-dimensional coordinates is defined by this workpiece coordinate system (Xw.

Yw) and coordinate data (x++
'/1) is also stored in the memory within the calculation means 6.

That is, as shown in FIG. 8, the mask article set on the mask table 10 shown in FIG. 23 is imaged. And this camera 5
The camera control means 8 detects the center position coordinates of the mask item on the camera coordinates (Xc, Yc) imaged by the camera control means 8, and transmits this data (Xl, )'+) to the memory of the calculation means 6 and stores it. . Note that "Oc" is the origin determined on the camera coordinates (Xc, Yc).

(2) Coordinate measurement of the object to be measured (on camera coordinates) As shown in FIG. 5, when a measurement start command signal is manually input from the main control means (not shown), the robot control means 7 moves The arm 4 is moved to all fixed points, and a movement completion signal is output to the camera control means 8. The camera control means 8 which received this robot movement completion signal,
As shown in FIGS. 9 and 10, the center coordinates of the detected portion 23 of the center positioning member 22 within the field of view of the camera 5 are detected, and this data (X21 y2) is transmitted to the calculation means 6. Next, in the calculation means 6, this measurement coordinate (X2
1 y2) and the mask coordinate (X++'/1) stored in advance in the memory of the calculating means 6 using the following formula (Step 5 in Figure 5 and Step 10 in Figure 6).
12).

ΔX=X2−Xi ΔY='It 72 (3) Conversion from camera coordinates to workpiece coordinates ΔX,
Since Δy is the displacement dimension of the object to be measured 1 at the camera coordinates (Xc, Yc), the calculation means 6 converts it into the workpiece coordinates (Xw, Yw) using the following formula (Fig. 11, and step 13 in FIG. 6).

X3 = xo - ΔX ''/3 = Yu - Δy In order to perform the above-mentioned 1 (Iljl stabilization), image the part to be measured with a camera from two or more different angles for one measurement point using the same procedure. The three-dimensional coordinates can be determined by

(Effects of the Invention) As described above, according to the three-dimensional coordinate measuring device of the present invention, the arm of an industrial robot, which has been taught in advance to operate in close proximity to a plurality of measurement points of the object to be measured, A position detection means for detecting the position of the point is provided, and a calculation means is provided for calculating the position error between the three-dimensional coordinate position of the measurement point and the three-dimensional coordinate position of the reference point with respect to the measurement point detected in advance by the detection means. Since it is configured to be H, the three-dimensional coordinates of the measurement point can be measured accurately and quickly, and furthermore, it has an excellent effect in terms of versatility.

[Brief explanation of drawings]

FIG. 1 is a conceptual diagram showing a three-dimensional coordinate measuring device according to an embodiment of the present invention, FIG. 2 is a perspective view showing a center positioning member used in the three-dimensional measuring device of the same embodiment, and FIG. , second
A cross-sectional view along the line ■-■ in the figure, Figure 4 is TV-I in Figure 2.
A sectional view taken along the V line, Figure 5.6, shows the robot! of the same embodiment.
・A flowchart showing the control of the control means, camera control means, and calculation means. FIGS. 7 to 11 are explanatory diagrams showing the coordinate conversion method of the same embodiment. FIG. 12 is a perspective view showing a conventional three-dimensional coordinate measuring device. It is. DESCRIPTION OF SYMBOLS 1...Measurement object, 2...Measurement point, 3...Industrial robot, 4...Arm, 5...Camera (position detecting means), 6...Calculating means.

Claims (1)

[Claims] An industrial robot (3) that has been taught in advance to operate in close proximity to a plurality of measurement points (2) of an object to be measured (1).
A position detection means (5) for detecting the position of the measurement point (2) is provided on the arm (4) of A three-dimensional coordinate measuring device comprising a calculation means (6) for calculating a positional error between a measurement point (2) and a three-dimensional coordinate position of a standard point.